Method of and apparatus for producing stacks of folded sheet material

ABSTRACT

Stacks of folded sheets with a C-fold, Z-fold, V-fold or other various kinds of folds are formed from a plurality of webs of flexible sheet material such as paper toweling or creped tissue. To form the stacks of folded sheets, the webs are longitudinally folded while traveling along a path to an accumulator at which the folded webs travel about a closed path a plurality of times and accumulate as a multiple series of webs stacked in an endless log. The endless log is severed at spaced intervals to form a plurality of individual stacks of folded sheets. When it is desired to interfold the sheets throughout the stack, the series of folded webs are first interfolded with each other while traveling to the accumulator whereat a portion of an outer one of the incoming series of webs is interleaved with a portion of an outer web of the partially formed log completing one revolution about the closed path on the accumulator.

United States Patent Furbeck et al.

METHOD OF AND APPARATUS FOR PRODUCING STACKS OF FOLDED SHEET MATERIAL [75] lnventors: Warren R. Furbeck; Charles A. Lee,

v both of Knoxville, Tenn. I [73] Assignee: International Paper Company, New

York, NY.

[22] Filed: July 17, 1972 [21] Appl. No: 272,413

[52] U.S. Cl. 270/40 [51] Int. Cl B411 1/30 [58] Field of Search 83/924, 54; 270/5-11, 32, 40-44, 52; 42/5521 [56] References Cited v I A UNITED STATES PATENTS 968,709 8/1910 Spalckhaver 270/42 3,066,932 12/1962 Greiner et al... 270/40 3,146,649 9/1964 Burger 83/54 X 3,163,066 12/1964 Beaulieu et al.... 83/924 X 3,372,885 3/1968 Nichols et al 242/5521 3,484,940 12/1969 Zell, Jr 83/924 X 3,488,013 1/1970 Sasaki..... 242/5521 3,556,510 l/l97l Tr'eff 270/52 Nov. 5, 1974 Primary Examiner-Melvin D. Rein Assistant Examiner-A. Heinz Attorney, Agent, or Firm--Fitch, Even, Tubin & Luedeka 5 7 ABSTRACT Stacks of folded sheets with a C-fold, Z-fold. V-fold or other various kinds of folds are formed from a plurality of webs of flexible sheet material such as paper toweling or creped tissue. To form the stacks of folded sheets, the webs are longitudinally folded while traveling along a path to an accumulator at which-the folded webs travel about a closed path a plurality of times and accumulate as a multiple series of webs stacked in an endless log. The endless log is severed at spaced intervals to form a plurality of individual stacks of folded sheets. When it is desired to interfold the sheets throughout the stack, the series of folded webs are first interfolded with each other while traveling to the accumulator whereat a portion of an outer one of the incoming series of webs is interleaved with a portion of an outer web of thepartially formed logcompleting one revolution about the closed path on the accumulator.

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1. A method of producing individual stacks of folded sheets from a plurality of webs of stretchable sheet material, said method comprising the steps of: Continuously, longitudinally folding each of a series of webs of sheet material while the webs travel along a feed path, traveling the folded webs about a closed path about a vertical axis, lifting the traveling webs as they make a revolution about said closed path and traveling the incoming webs therebeneath, and accumulating a multiple series of the folded webs in a vertically stacked condition constituting an endless log at an accumulating station, and severing the endless log at predetermined and spaced locations to form a plurality of individual stacks of folded sheets. 9
 2. A method in accordance with claim 1 including the further step of: cutting the endless log while in a closed loop at the accumulating station, and feeding one end of the severed log forwardly from the accumulating station to a severing station and then severing the log into the individual stacks.
 3. A method in accordance with claim 1 including the steps of drawing the series of web along a straight line feed path to the accumulating station and traveling the folded webs about a circular path which is tangential to said straight line feed path.
 4. A method of producing individual stacks of folded sheets from a plurality of webs of stretchable sheet material, said method comprising the steps of: continuously, longitudinally folding a series of webs of sheet material, superimposing the folded webs to form a series of folded webs and drawing the series of webs along a path tangential to and leading to an accumulating wheel rotatable about a fixed axis and having a circumferential supporting means for said webs, continuously winding webs with their edges in planes substantially perpendicular to said axis and at a substantially constant radius from said axis and continuously winding said stack of folded webs about said accumulating wheel for a plurality of revolutions of said accumulating wheel to form a circular log having multiple layers of said stacked folded webs thereon, cutting the circular log while on said accumulating wheel to form an elongated log, feeding one end of said log from said accumulating wheel toward a severing station along another path from said accumulating wheel, and severing said elongated log at spaced locations to form said individual stacks of folded sheets.
 5. A method in accordance with claim 4 including the further steps of: stopping said accumulating wheel prior to cutting said circular log, straightening said elongated log from said circular configuration, and banding said straightened elongated log with a wrapper band prior to severing the banded log into the individual banded stacks of folded sheets.
 6. A method in accordance with claim 4 including the further step of accumulating the stacks of folded webs vertically on the accumulating wheel and traveling the incoming series of webs beneath the webs already on the accumulating wheel.
 7. A method in accordance with claim 6 including the further steps of: compressing the elongated log and banding the compressed elongated log with a wrapper band prior to severing the banded log into individual banded stacks of folded sheets.
 8. A method of producing individual stacks of interfolded sheets from a plurality of webs of flexible material comprising, continuously, longitudinally folding a plurality of webs of sheet material, interfolding adjacent folds of adjacent webs to provide a series of interfolded webs traveling along a predetermined path to an accumulating station, accumulating said interfolded webs while traveling about a closed path at said accumulating station, interfolding at the accumulating station an outermost fold of the outer web of the series of interfolded incoming webs with an outermost fold of the outer one of the series of webs traveling about said closed path whereby the successive loops of webs are interfolded with one another to constitute a log of interfolded webs, and severing the log at spaced locations to form the individual stacks of interfOlded sheets.
 9. A method of accumulating a circular log of folded webs from a stack of incoming folded webs of stretchable sheet material, said method comprising the steps of: feeding said stack of incoming webs along substantially linear path to a tangential intersection with an accumulator rotatable about a vertical axis, bending said incoming series of webs about said accumulator sheel to form a circular stack with the inner edges of said webs aligned at a substantial constant radius from said vertical axis and with the webs in substantially horizontal planes, shifting vertically the circular stack of webs on the accumulator adjacent said tangent point and joining the incoming stack of webs with the vertically shifted circular stack of webs on the accumulator.
 10. A method in accordance with claim 9 including the further step of confining the webs in the circular stack between overlying and underlying surfaces to hold the webs in flat horizontal positions while bent and accumulated into said circular stack.
 11. A method of accumulating a circular stack of webs from an incoming linear stack of webs, said method comprising the steps of: continuously traveling said linear stack of webs along a substantially linear path to an accumulating station having a circular accumulator rotatable about a vertical axis to intersect the linear path at a tangent point, bending the linear incoming stack of webs about an annular surface on said accumulator and into a circular stack, raising the circular stack of webs from a horizontally disposed annular support on said accumulator at a position adjacent said tangential intersection, inserting continuously said incoming linear stack of webs beneath the lifted circular stack of webs, applying a force to the top of the circular stack to maintain webs in flat horizontal positions, and controlling the tension in webs to within predetermined limits to avoid loose or overly taut webs.
 12. A method in accordance with claim 11 in which said all of webs in said circular stack are interfolded said method comprising the further steps of: interfolding each of the webs of said linear stack, opening a fold in the outermost web of said linear stack adjacent said tangential intersection, opening a fold on a lowermost web of the circular stack of webs on said accumulator, and interleaving the opened folds of said respective webs adjacent said tangential intersection.
 13. A method of producing individual stacks of folded sheets from a plurality of webs of stretchable sheet material, said method comprising the steps of: continuously, longitudinally folding each of a series of webs of sheet material while the webs travel along a feed path, interfolding portions of each of the series of webs into interfolded relationship and subsequently traveling the interfolded webs about a closed path, traveling the folded webs about a closed path a plurality of times, accumulating a multiple series of the folded webs in a vertically stacked condition constituting an endless log at an accumulating station, continuously interfolding an edge portion of an outer web of the stacked webs finishing a lap about said closed path with an edge portion of an outer web of the series of interfolded webs incoming into the closed path to provide a stack of webs interfolded throughout its height, and severing the endless log at predetermined and spaced locations to form a plurality of individual stacks of folded sheets.
 14. A method of producing individual stacks of folded sheets from a plurality of webs of stretchable sheet material, said method comprising the steps of: continuously, longitudinally folding a series of webs of sheet material, superimposing the folded webs to form a series of folded webs and drawing the series of webs along a path tangential to and leading to an accumulating wheel, interfolding a portion of each web of the series of webs prior to being accumulated, continuously winding said stack of folded webs about said accumulAting wheel for a plurality of revolutions of said accumulating wheel to form a circular log having multiple layers of said stacked folded webs thereon, continuously interfolding the outermost portion of an outermost web of an incoming series of interfolded webs with a portion of an outermost web of the circular log being formed on the accumulator wheel so that all of the webs on the accumulator wheel are in interfolded relationship throughout the log, cutting the circular log while on said accumulating wheel to form an elongated log, feeding one end of said log from said accumulating wheel toward a severing station along another path from said accumulating wheel, and severing said elongated log at spaced locations to form said individual stacks of folded sheets.
 15. A method of accumulating a circular log of folded webs from a stack of incoming stretchable sheet material, said method comprising the steps of: means at said folding station for interfolding portions of said series of webs into interfolded relationship with each other, feeding said stack of incoming webs along a substantially linear path to a tangential intersection with an accumulator rotatable about a vertical axis, means at said accumulating station for interfolding an outer portion of one of the webs of the incoming series of webs into interfolded relationship with a portion of the series of webs finishing a lap about said closed path whereby all of the webs in the log on the accumulating means are interfolded with each other bending said incoming series of webs about said accumulator wheel to form a circular stack, shifting vertically the circular stack of webs on the accumulator adjacent said tangent point and joining the incoming stack of webs with the vertically shifted circular stack of webs on the accumulator.
 16. An apparatus for producing individual stacks of folded sheets from a plurality of webs of stretchable sheet material, said apparatus comprising folding means at a folding station for folding each of a series of webs of sheet material with at least one longitudinally extending fold while the webs travel along a feed path, an accumulating means for receiving said series of folded webs and for carrying the webs about a closed path about a fixed axis for a plurality of times, support means on said accumulating means for supporting said webs with inner edges thereof aligned at a predetermined distance from said axis and with said folded webs being stacked in planes substantially perpendicular to said axis and to accumulate said folded webs in a stacked condition constituting an endless log at an accumulating station, means for displacing the accumulating folded webs on said support means and for guiding the incoming webs on to said support means, and means for severing the endless log at predetermined and spaced locations to form a plurality of individual stacks of folded sheets.
 17. An apparatus in accordance with claim 16 in which a cutting means severs the endless log while on said accumulating means and in which a conveying means carries said log from said accumulating station to said severing means.
 18. An apparatus in accordance with claim 17 in which said accumulating means comprises a rotatable wheel having a circular closed path for accumulating a circular log of folded webs thereon, said circular closed path being tangential to the feed path of said series of webs from said folding means.
 19. An apparatus in accordance with claim 16 in which a banding means is provided for banding said log with a band to hold said folded sheets in a stacked condition and in which said severing means severs said banded sheets subsequent to banding so that the stacks are already banded when severed from said log.
 20. An apparatus for producing individual stacks of interfolded sheets from a plurality of webs of sheet material, said apparatus comprising means at a folding station for forming continuous, longitudinally extending folds in each of a series of webs of sheet material, meAns for closing the portions of adjacent folds of adjacent webs into interfolded relationship while traveling along a predetermined path to an accumulating station, an accumulating means at said accumulating station for carrying said interfolded webs about a closed path for a series of cycles for stacking the incoming series of webs into an endless log, means interfolding a fold portion of one of the incoming series of webs from the folding station with a fold portion of one of the webs completing a cycle about said closed path to cause the webs on the accumulator to be interfolded with each other throughout the height of the stacked condition, and means for severing the log at spaced location to form individual stacks of interfolded sheets.
 21. An apparatus in accordance with claim 20 in which said means for interfolding one of the incoming series of webs with the webs making a cycle on the accumulating means comprises an interfolding shoe for forming troughs in said webs for inserting a longitudinally extending portion of a web on the accumulating means into a portion of the incoming web of the series of webs.
 22. An apparatus in accordance with claim 21 in which said interfolding shoe lifts the stack of webs on the accumulating means while forming the troughs to interfold the webs together.
 23. An apparatus in accordance with claim 20 in which means are provided for sensing the tension in the webs traveling along said predetermined path to said accumulating station, and means are provided for varying travel speed of said incoming webs relative to the travel speed of said webs traveling about said closed path to cause the tension in said webs to be within predetermined limits of tension.
 24. An apparatus in accordance with claim 20 in which said accumulator comprises a wheel rotatable about a vertical axis, a support on said accumulator wheels supports the webs in a circular stacked condition on said wheel, and means on said accumulator confines and flattens the webs being stacked on said support.
 25. An apparatus for producing individual stacks of folded sheets from a plurality of webs of flexible sheet material, said apparatus comprising: folding means at a folding station for folding each of a linear stack of webs of sheets material with at least one longitudinally extending fold while the webs travel along a substantially linear feed path, means for feeding said sheets along said feed path to an accumulating station, an accumulating wheel at said accumulating station rotatable about a vertical axis for receiving said series of folded webs and for carrying the webs in a circular path for a plurality of times to accumulate the incoming webs in a circular stack constituting an endless log, means adjacent a juncture of said feed path and said circular path to shift vertically the circular stack of webs on the accumulator wheel relative the plane of linear stack of webs to allow joining of the incoming webs with the circular stacked webs, means for confining the circular stack of webs and for holding the same in flat horizontal positions on said accumulator wheel, means for adjusting the speed of travel of said linear stack of webs relative to the speed of web travel on said accumulator wheel to maintain tension in the webs within predetermined limits of tension, and means for severing the endless log at predetermined and spaced locations to form a plurality of individual stacks of folded sheets.
 26. Apparatus in accordance with claim 25 in which said stack separating means comprises a surface for lifting the bottom of the stack on the accumulating wheel and a surface for supporting and guiding said incoming webs to a tangent point for insertion beneath the lifted circular stack of webs.
 27. An apparatus in accordance with claim 26 in which said confining and flattening means for said stack comprises an overlying ring means resting on the top of the circular stacked webs on the accumulator wheel for holding the webs in a substantially horizontal flat condition while being accumulated.
 28. An apparatus in accordance with claim 26 in which said stack separating means further comprises an interfolding shoe for opening a fold in the lowermost web of the circular stack of webs and for opening an upper fold on the incoming linear stack of webs, said interfolding shoe guiding said open folds into superimposed relationship for interleaving upon discharge from said stack separating means.
 29. In an accumulator for interfolding a fold of an incoming linear stack of webs traveling along a linear path with a circular stack of webs traveling through said interfolding shoe, a shoe means comprising a first support surface for said linear stack of webs, a camming surface for lifting the circular stack of webs on an accumulator, a second support surface for receiving said lifted stack and for guiding the same to adjacent a tangent point between the circular path and the intersecting linear path, a first interleaving surface for opening a trough within the folds in the lowermost web of the lifted webs, a second interleaving surface for forming a trough within the folds of the upper web of the incoming stack of webs, a supporting surface for supporting the incoming stack of webs for travel along a linear path to the tangent point, said first and second interleaving surfaces extending toward said tangent point for guiding said opened folds into superimposed relationship so that upon discharge from said interfolding shoe means and the closing of said folds and the closing of the troughs the webs are all interfolded.
 30. An accumulator in accordance with claim 29 in which an inclined plate extends between said first and second supporting surfaces, said first interleaving surface comprising the underside of said inclined plate, and said second interleaving surface comprising the upper side of said inclined plate.
 31. An accumulator in accordance with claim 29 in which a lower horizontal extending plate has its upper surface constituting said first supporting surface, an upper plate is disposed parallel to said lower plate and spaced therefrom with said incline plate being intermediate said upper and lower plates, said upper surface of said upper plate constituting said second supporting surface and said camming surface comprises the upper surface of a downwardly inclined plate projecting from said upper plate.
 32. An apparatus for producing individual stacks of folded sheets from a plurality of webs of stretchable sheet material, said apparatus comprising folding means at a folding station for folding each of a series of webs of sheet material with at least one longitudinally extending fold while the webs travel along a feed path, means at said folding station for interfolding portions of said series of webs into interfolded relationship with each other, an accumulating means for receiving said incoming series of folded webs and for carrying the webs about a closed path for a plurality of times to accumulate said folded webs in a stacked condition constituting an endless log at an accumulating station, means at said accumulating station for interfolding an outer portion of one of the outer webs of the incoming series of webs into interfolded relationship with a portion of the series of webs finishing a lap about said closed path whereby all of the webs in the log on the accumulating means are interfolded with each other and means for severing the endless log at predetermined and spaced locations to form a plurality of individual stacks of folded sheets. 